In a full automatic biochemical analyzer, a sample plate is used to carry a variety of test tubes which hold samples, and rotates intermittently according to a predetermined program to transmit the test tubes which hold the samples to positions where the samples are to be extracted such that sampling needles extract the samples. During rotation of the sample plate, a bar code scanner reads sample information under control of the program. Therefore, it is required to adopt a sample plate for supporting bar code scanning. The existing sample plate are provided with sample slots distributed uniformly along the circumference thereof and clear slots for allowing bar code scanning light to pass, in which the clear slot communicates with the sample slot and the axis of the clear slot passes through the center of the circle of the corresponding sample slot and that of the sample plate, thereby causing an unreasonable incident angle in which the bar code scanning light is projected on the bar code on the test tube.